Quote Originally Posted by ephekt
My whole point was that if we do rule on this legally, using social definitions is a horribly stupid thing to do, since as everyone seems to agree, they're all arbitrary.
So as coq says, what should we use? There's nothing else. You have talked about using scientific definitions, but as I said in my previous post, that doesn't in the slightest bit remove the need to make an arbitrary decision about where to place the line. Science can identify various points in embryonic/fetal development but it can't tell us which one marks the beginning of personhood because personhood is itself a socially constructed and defined concept, not a scientific one. THERE IS NO WAY to define a point at which it begins in any way that isn't arbitary and subjective. The definition is always going to be culturally determined. So no, using social definitions isn't a horribly stupid thing to do. It's the only thing we can do.